JP3832476B2 - Wafer prober - Google Patents

Description

  The present invention relates to a wafer prober that holds a wafer and heats it to a predetermined temperature in a semiconductor inspection process.

  Conventionally, in the semiconductor manufacturing process, a so-called probing process is provided in order to inspect the electrical characteristics of a semiconductor wafer. Conventionally, various structures have been proposed for a prober used for holding and heating a wafer in this probing process. As such a prober, for example, a metal wafer prober has been conventionally used as described in JP-A-11-31724.

  Recently, in order to reduce the manufacturing cost, the diameter of the wafer has been increased from 8 inches to 12 inches, and accordingly, the wafer prober for holding the wafer has become more than 300 mm in diameter. Yes. At the same time, there is an increasing demand for heat uniformity on the wafer surface heated by the wafer prober, and usually ± 1.0% or less, more preferably ± 0.5% or less is required.

  In response to such high thermal uniformity requirements, when a wafer is placed on the chuck top conductor layer of a wafer prober, a gap is formed between the wafer placement surface and the wafer, so that the wafer can be heated uniformly. Therefore, it has been pursued to increase the flatness of the wafer mounting surface by precision processing. However, with the increase in the diameter of the wafer prober described above, it is becoming difficult to realize the above requirement for the thermal uniformity of the wafer surface.

Japanese Patent Laid-Open No. 11-31724

  As described above, in order to improve the thermal uniformity of the wafer surface held and heated by the wafer prober, it has been conventionally attempted to increase the flatness of the wafer mounting surface in the chuck top conductor layer of the wafer prober. However, in recent years, it has become difficult to satisfy soaking requirements as the diameter of wafers has increased.

  Further, in the conventional metal wafer prober, the wafer mounting surface is gradually deformed by the pressure of a large number of tester pins pressed against the wafer, the wafer is damaged, or the measurement pins of the probe card do not hit the wafer. The problem was occurring. Therefore, in order to prevent the wafer from being damaged or the measurement pin of the probe card from being hit, the present situation is to increase the thickness of the wafer prober. However, as the thickness increases, the heat capacity of the wafer prober increases, which causes another problem that it takes a long time to raise or lower the temperature.

  Further, the wafer prober is provided with a plurality of vacuum suction holes on the wafer mounting surface of the chuck top conductor layer in order to suck and securely fix the wafer. For example, a substantially concentric groove is formed on the wafer mounting surface, suction holes are formed in the respective grooves, and vacuum suction is performed through these holes, so that the wafer is closely fixed to the wafer mounting surface. Yes.

  However, as described above, when the wafer mounting surface warps during heating of the wafer, the vacuum suction is insufficient depending on the shape of the wafer, and the wafer cannot be securely fixed. In such a state, if the probe card is pressed against the wafer with a predetermined pressure, the wafer will move, the continuity between the wafer and the chuck top conductor layer will not be sufficient, or in the worst case, the wafer will be damaged. There was a problem of doing.

  In view of such a conventional situation, the present invention can increase the flatness of the wafer mounting surface in the chuck top conductor layer in a high temperature range in which the wafer is heated in the semiconductor inspection process. An object of the present invention is to provide a wafer prober with improved thermal properties and improved reliability.

  In order to achieve the above object, the present invention is a wafer prober for holding and heating a wafer in a semiconductor inspection process, having a conductor layer on the surface of a ceramic substrate, and a surface opposite to the surface on which the conductor layer is formed or There is provided a wafer prober comprising a resistance heating element inside, wherein a warp shape of a wafer mounting surface in the conductor layer is a concave shape of 0.001 to 0.7 mm / 300 mm when not heated.

  In the wafer prober of the present invention, it is preferable that the ceramic substrate is made of at least one selected from aluminum nitride, silicon nitride, aluminum oxynitride, and silicon carbide. The resistance heating element is preferably made of at least one selected from tungsten, molybdenum, tantalum, platinum, palladium, silver, nickel, and chromium.

  According to the present invention, it is possible to increase the flatness of the wafer mounting surface in the wafer heating temperature range in the semiconductor inspection process by controlling the shape of the warp of the wafer mounting surface, and thus the wafer surface during heating. In addition, it is possible to provide a highly reliable wafer prober that is excellent in heat uniformity and has no positional deviation or breakage of the wafer.

  As a result of studying the flatness of the wafer placement surface of the wafer prober, the inventors have found that the conventional wafer prober is in a warped state where the wafer placement surface is convex (hereinafter also referred to as a + direction) when not heated. Further, it has been found that when the resistance heating element is heated by energization and the temperature rises and the Young's modulus decreases, the convex warpage of the wafer mounting surface further increases in the + direction.

  Therefore, the present inventors have developed a wafer prober in which a chuck top conductor layer is formed on the surface of a ceramic heater. When the wafer prober is not heated, the wafer mounting surface of the conductor layer is concave ( Hereinafter, it was adjusted so as to be also referred to as “− direction”. That is, the wafer prober of the present invention comprises a ceramic heater having a resistance heating element on the surface or inside of a ceramic substrate, and a conductor layer provided on the surface where the resistance heating element is not formed. The shape of the warp on the surface is a concave shape of 0.001 to 0.7 mm per 300 mm length of the wafer mounting surface when not heated (at room temperature).

  By making the shape of the warp when the wafer placement surface is not heated concave, the ceramic heater warps in the opposite + direction at the high temperature range during actual wafer heating. The flatness of the surface is improved and the wafer can be securely held in close contact. As a result, the contact failure between the wafer and the chuck top conductor layer can be eliminated, the wafer can be prevented from being displaced and damaged, and all the measurement pins of the probe card can be applied to the wafer.

  In particular, in the wafer prober of the present invention using a ceramic heater, the thermal uniformity of the wafer surface during heating can be improved. Specifically, when a ceramic heater having a thermal conductivity of 100 W / mK or more is used, it is ± 0.5% or less, and in the case of a ceramic heater of 10 to 100 W / mK, it is extremely excellent, that is, ± 1.0% or less. It is possible to achieve soaking on the wafer surface.

  In order to manufacture the wafer prober of the present invention, first, a ceramic heater having a resistance heating element is produced on the surface or inside of a ceramic substrate, and the surface where the resistance heating element is not formed is subjected to processing such as polishing. The shape of the warp at the time of non-heating is formed in the concave shape described above. Thereafter, a conductor layer is formed on the surface having the warped shape formed into a concave shape, thereby forming a chuck top conductor layer in contact with the back surface of the wafer. In this way, a wafer prober having a conductor layer having a concave shape of 0.001 to 0.7 mm / 300 mm when the wafer mounting surface is warped is not heated.

  Next, a method for manufacturing a ceramic heater used for the wafer prober of the present invention will be described by taking as an example the case where the heater material is aluminum nitride (AlN). Even when the heater material is other than aluminum nitride, the ceramic heater can be manufactured in substantially the same manner by appropriately selecting and adjusting the sintering aid and the sintering conditions.

The AlN raw material powder preferably has a specific surface area of 2.0 to 5.0 m ² / g. When the specific surface area is less than 2.0 m ² / g, the sinterability of AlN is lowered. When the specific surface area exceeds 5.0 m ² / g, the aggregation of the powder becomes very strong and handling becomes difficult. Moreover, since the thermal conductivity of a sintered compact will fall when the amount of oxygen contained in raw material powder exceeds 2 weight%, 2 weight% or less is preferable. Furthermore, the amount of metal impurities other than aluminum contained in the raw material powder is preferably 2000 ppm or less. When the amount of metal impurities exceeds 2000 ppm, the thermal conductivity of the sintered body is lowered. Particularly, a group 4 element such as Si or an iron group element such as Fe as a metal impurity acts to lower the thermal conductivity of the sintered body. Since it is high, the content is preferably 500 ppm or less.

  Since AlN is a hardly sinterable material, it is preferable to add a sintering aid to the raw material powder. As the sintering aid to be added, a rare earth element compound is preferable. The rare earth element compound reacts with the aluminum oxide or aluminum oxynitride present on the surface of the AlN particles during sintering to promote densification of AlN and to reduce the thermal conductivity of the AlN sintered body. By removing the oxygen which becomes, the thermal conductivity of the AlN sintered body is improved.

  As such a rare earth element compound, an yttrium compound having a particularly remarkable function of removing oxygen is preferable. As the rare earth element compound, an oxide, nitride, fluoride, stearic acid compound, or the like can be used. Of these, oxides are particularly preferable because they are inexpensive and easily available. In addition, since the stearic acid compound has high affinity with the organic solvent, mixing the AlN raw material powder and the sintering aid with the organic solvent is preferable because the mixing property can be improved.

  The addition amount of the sintering aid is preferably in the range of 0.01 to 5% by weight. If it is less than 0.01% by weight, it is difficult to obtain a dense sintered body, and the thermal conductivity of the AlN sintered body is lowered. On the other hand, if it exceeds 5% by weight, a large amount of sintering aid is present at the grain boundaries of the AlN sintered body, and this also tends to cause a decrease in thermal conductivity. More preferably, by setting the additive amount of the sintering aid to 1% by weight or less, the sintering aid does not exist at the triple point of the grain boundary, so that a high thermal conductivity AlN sintered body can be easily obtained. Become.

  Next, a solvent and a binder are added to these AlN raw material powder and sintering aid powder, and further, a dispersant and a glaze are added as necessary, and mixed to prepare a raw material slurry. As a mixing method, ball mill mixing, ultrasonic mixing, or the like is possible. An AlN sintered body can be obtained by molding and sintering the obtained raw material slurry. There are two types of methods, a post metallization method and a cofire method.

  First, the post metallization method will be described. Granules are produced from the raw material slurry adjusted as described above by a technique such as a spray dryer. This granule is inserted into a predetermined mold and press-molded to obtain a molded body. The pressing pressure at this time is desirably 9.8 MPa or more. This is because when the pressure is less than 9.8 MPa, the strength of the molded body is often not sufficiently obtained and is easily damaged by handling.

Although the density of a molded object changes with content of a binder, and the addition amount of a sintering auxiliary agent, it is preferable that it is 1.5-2.5 g / cm < ³ >. When the density is less than 1.5 g / cm ³ , the distance between the raw material powder particles becomes relatively large, and the sintering becomes difficult to proceed. Moreover, when the density of a molded object exceeds 2.5 g / cm < ³ >, it will become difficult to remove the binder in a molded object fully by the degreasing process of the following process.

  The obtained molded body is degreased by heating in a non-oxidizing atmosphere. This is because when the degreasing treatment is performed in an oxidizing atmosphere such as the air, the surface of the AlN powder is oxidized and the thermal conductivity of the sintered body is lowered. As the non-oxidizing atmosphere gas, nitrogen or argon is preferable. As for the heating temperature of a degreasing process, 500-1000 degreeC is preferable. If the temperature is less than 500 ° C., the binder cannot be sufficiently removed, and excess carbon remains in the molded body after the degreasing treatment, so that the excess carbon causes the aluminum nitride to be sintered in the subsequent sintering step. Inhibit. Also, at a temperature exceeding 1000 ° C., the amount of remaining carbon becomes too small, so that the oxygen in the oxide film present on the surface of the AlN powder cannot be removed during sintering, and the amount of oxygen in the sintered body is large. As a result, the thermal conductivity decreases.

  For these reasons, the amount of carbon remaining in the molded body after the degreasing treatment is preferably 0.1 to 1.0% by weight. If more than 1.0% by weight of carbon remains in the degreased molded product, it will be difficult to obtain a dense sintered product because it inhibits the sintering of aluminum nitride as described above. is there. On the other hand, if the residual carbon content is less than 0.1% by weight, the thermal conductivity of the obtained sintered body tends to decrease.

  The molded body after the degreasing treatment is sintered at a temperature of 1700 to 2000 ° C. in a non-oxidizing atmosphere such as nitrogen or argon. The moisture contained in the atmospheric gas such as nitrogen used at this time is preferably −30 ° C. or less in terms of dew point. When it contains more moisture than this, AlN reacts with moisture in the atmospheric gas during sintering to form oxynitrides, which may reduce the thermal conductivity of the sintered body. Further, the amount of oxygen in the atmospheric gas is preferably 0.001% by volume or less. When the amount of oxygen is large, the surface of AlN is oxidized, and there is a possibility that the thermal conductivity is lowered.

  The jig used at the time of sintering is preferably a boron nitride (BN) compact. The BN compact has sufficient heat resistance with respect to the sintering temperature, and its surface has solid lubricity, so that the friction between the jig and the compact when the compact shrinks during sintering. It can be made small and a sintered body with little distortion can be obtained.

  The obtained AlN sintered body is processed as necessary in order to form a resistance heating element and other necessary electric circuits in the next step. For example, in order to screen-print the conductive paste, the surface of the sintered body is polished, and the surface roughness Ra is preferably 5 μm or less, and more preferably 1 μm or less. If the surface roughness exceeds 5 μm in Ra, defects such as pattern bleeding and pinholes are likely to occur when a circuit is formed by screen printing.

  Further, the parallelism of the processed surface at this time is preferably 0.5 mm or less, and more preferably 0.1 mm or less. If the parallelism exceeds 0.5 mm, the thickness of the conductive paste may vary greatly during screen printing. Furthermore, the flatness of the screen printing surface is also preferably 0.5 mm or less, and more preferably 0.1 mm or less. If the flatness exceeds 0.5 mm, the variation in the thickness of the conductive paste may also increase.

  Next, a conductive paste is applied to the surface of the polished AlN substrate by screen printing and baked to form an electric circuit. The conductor paste can be obtained by mixing a metal powder with a binder and a solvent, adding a metal oxide powder as necessary, and kneading. The metal powder to be used is preferably a refractory metal when forming a resistance heating element, and tungsten, molybdenum, or tantalum is particularly preferred from the viewpoint of matching the thermal expansion coefficient with ceramics.

In order to increase the adhesion strength with AlN, a metal oxide powder can be added to the conductor paste. The metal oxide powder is preferably an oxide of a 2A group element or a 3A group element, Al ₂ O ₃ , SiO ₂ or the like. In particular, yttrium oxide is particularly preferable because it has very good wettability to AlN. The addition amount of these metal oxide powders is preferably in the range of 0.1 to 30% by weight. When the addition amount is less than 0.1% by weight, the adhesion strength between the formed electric circuit and AlN is lowered. On the other hand, if it exceeds 30% by weight, the electric resistance value of the electric circuit becomes too high, which is not preferable.

  The thickness of the conductive paste to be formed is preferably 5 μm or more and 100 μm or less in terms of the thickness after drying. When the thickness is less than 5 μm, the electrical resistance value becomes too high, and the adhesion strength also decreases. Also, a thickness exceeding 100 μm is not preferable because the adhesion strength decreases.

  When the circuit pattern to be formed is a resistance heating element circuit, it is preferable that the pattern interval is 0.1 mm or more. This is because when the current is less than 0.1 mm, a leakage current may be generated depending on the applied voltage and temperature, causing a short circuit when a current is passed through the heating element. For this reason, the pattern interval is more preferably 1 mm or more, and most preferably 3 mm or more.

  The conductive paste having the circuit pattern formed on the AlN substrate is then degreased in a non-oxidizing atmosphere such as nitrogen or argon. The degreasing temperature is preferably 500 ° C. or higher. When the degreasing temperature is less than 500 ° C., the binder in the conductive paste is not sufficiently removed, and carbon remains, so that a metal carbide is formed when baked to increase the electric resistance value of the electric circuit. .

  The baking after degreasing is preferably performed at a temperature of 1500 ° C. or higher in a non-oxidizing atmosphere such as nitrogen or argon in the case of the high melting point metal. When the firing temperature is less than 1500 ° C., the particle growth of the metal powder does not proceed, the electrical resistance value after firing becomes too high, and the bond between the metal particles is weak, so that the adhesion is lowered. The firing temperature should not exceed the sintering temperature of the ceramic. When the conductive paste is baked at a temperature exceeding the sintering temperature of the ceramic, the sintering aid contained in the ceramic begins to evaporate, and further, the particle growth of the metal powder in the conductive paste is promoted, and adhesion with the ceramic is promoted. Strength decreases.

In order to ensure insulation of the formed electric circuit, an insulating layer can be formed thereon. The material of the insulating layer is not particularly limited as long as the reactivity with the electric circuit is small and the difference in thermal expansion coefficient from AlN is 5.0 × 10 ⁻⁶ / K or less. In some cases, crystallized glass or AlN can be used. The amount of sintering aid added to the AlN powder at this time is preferably 0.01% by weight or more. If it is less than 0.01% by weight, the AlN insulating layer will not be densified, and it will be difficult to ensure insulation from the metal layer. On the other hand, if the amount of the sintering aid exceeds 20% by weight, excessive sintering aid may permeate into the metal layer of the electric circuit, and the electric resistance value of the electric circuit may change.

  As a method for forming the insulating layer, these materials may be pasted, for example, screen printed with a predetermined thickness, degreased as necessary, and then fired at a predetermined temperature. Although there is no restriction | limiting in particular in the thickness which apply | coats a paste, It is preferable that it is 5 micrometers or more. This is because it is difficult to ensure insulation when the thickness is less than 5 μm.

  Further, as the metal powder used for the conductive paste, platinum, palladium, silver, or a mixture or alloy thereof can be used in addition to the above-described high melting point metal. For example, by adding palladium or platinum to silver in the paste, the volume resistivity of the conductor can be increased, so that the addition amount can be adjusted to obtain an electrical resistance value corresponding to the electrical circuit. it can. Moreover, since these added metals of palladium and platinum have an effect of preventing migration between circuit patterns, it is preferable to add 0.1 parts by weight or more with respect to 100 parts by weight of silver.

  Furthermore, Ni, Cr, or a mixture or alloy thereof can be used as the metal powder used for the conductive paste. In particular, by adding about 20% by weight of Cr to Ni, it is possible to form a resistance heating element having high electrical resistance and excellent heat resistance and corrosion resistance. In order to reduce the cost, Fe may be added up to 25% by weight, or in order to increase the workability, 1% by weight of Mn may be added.

  Even when these metal powders are used, it is preferable to add metal oxide powders in order to ensure adhesion with AlN. For example, powders such as aluminum oxide, silicon oxide, copper oxide, boron oxide, zinc oxide, lead oxide, rare earth oxide, transition metal element oxide, and alkaline earth metal oxide can be added. The addition amount is preferably 0.1 to 50% by weight. When the addition amount is less than 0.1% by weight, the adhesion with AlN is lowered, which is not preferable. On the other hand, if the amount added exceeds 50% by weight, sintering of metal components such as silver is inhibited.

  When forming a resistance heating element and other electric circuits using these metal powders, a binder and a solvent are mixed with the metal powder, and a metal oxide powder is added as necessary, and kneaded to obtain a paste. A circuit pattern can be formed by screen printing using this paste in the same manner as described above. In this case, the formed circuit pattern is baked in a temperature range of 700 ° C. to 1000 ° C. in an inert gas atmosphere such as nitrogen or in the air.

  Furthermore, also in this case, in order to ensure the insulation between the circuits, the insulating layer can be formed by applying crystallized glass, glaze glass, resin, or the like and baking or curing. As the kind of glass, borosilicate glass, lead oxide, zinc oxide, aluminum oxide, silicon oxide and the like can be used. A solvent or binder is added to these powders to form a paste, which is then applied by screen printing. Although there is no restriction | limiting in particular in the thickness to apply | coat, It is preferable that it is 5 micrometers or more. This is because it is difficult to ensure insulation when the thickness is less than 5 μm. Further, the firing temperature is preferably lower than the temperature at which the electric circuit is formed. This is because the resistance value of the electric circuit greatly changes when firing at a temperature higher than the circuit firing temperature.

  The ceramic heater thus obtained can be further laminated with a ceramic substrate or a similar ceramic heater as required. This lamination is preferably performed via a bonding agent. That is, a 2A group element compound, a 3A group element compound, a binder and a solvent are added to an aluminum oxide powder or an AlN powder, and a paste is used as an adhesive, which is applied to the joint surface by a method such as screen printing. Although there is no restriction | limiting in particular in the thickness of the bonding agent to apply | coat, it is preferable that it is 5 micrometers or more. This is because when the thickness is less than 5 μm, bonding defects such as pinholes and bonding unevenness easily occur in the bonding layer.

  Next, the ceramic substrate or ceramic heater to which the bonding agent has been applied is degreased at a temperature of 500 ° C. or higher in a non-oxidizing atmosphere. Thereafter, the ceramic substrates or ceramic heaters to be stacked are superposed and bonded by heating in a non-oxidizing atmosphere while applying a predetermined load. The applied load is preferably 5 kPa or more, and if the load is less than 5 kPa, sufficient bonding strength cannot be obtained or bonding defects are likely to occur. The heating temperature for bonding is not particularly limited as long as the ceramics are sufficiently fixed to each other through the bonding layer, but is preferably 1500 ° C. or higher. If it is less than 1500 degreeC, sufficient joint strength is hard to be obtained and it will be easy to produce a joint defect. Moreover, it is preferable to use nitrogen, argon, etc. for the non-oxidizing atmosphere at the time of degreasing and joining.

  As described above, a ceramic heater serving as an energization heating heater can be obtained. The electrical circuit does not use the conductive paste as described above. For example, in the case of a resistance heating element circuit, a molybdenum wire (coil) is used, and in the case of an electrostatic adsorption electrode or an RF electrode, a network of molybdenum or tungsten is used. It is also possible to use a body (mesh).

  In that case, the molybdenum coil or mesh can be incorporated in the AlN raw material powder and can be produced by hot pressing. The hot press temperature and atmosphere may be in accordance with the sintering temperature and atmosphere of the AlN, but the hot press pressure is preferably 0.98 MPa or more. If it is less than 0.98 MPa, a gap may be formed between the coil or mesh and AlN, which may cause temperature unevenness on the wafer mounting surface or decrease the strength of the wafer prober produced. .

  Next, the cofire method will be described. The raw material slurry described above is formed into a sheet by a doctor blade method. Although there is no restriction | limiting in particular regarding sheet forming, It is preferable that the thickness of a sheet shall be 3 mm or less after drying. This is because if the thickness of the sheet exceeds 3 mm, the amount of drying shrinkage of the slurry increases, so that the probability of cracking in the sheet increases.

  An electric circuit pattern having a predetermined shape is formed on the sheet by applying a conductive paste by a method such as screen printing. The same conductive paste as that described in the post metallization method can be used. However, in the cofire method, there is no problem even if the oxide powder is not added to the conductive paste.

  Next, the sheet on which the circuit pattern is formed and the sheet on which the circuit pattern is not formed are set at a predetermined position and overlapped, and a solvent is applied between the sheets as necessary. In the laminated state, heating is performed as necessary, and pressure is applied to integrate them. When heating, it is preferable that heating temperature is 150 degrees C or less. This is because if the sheet is heated to a temperature exceeding 150 ° C., the laminated sheets are greatly deformed. Moreover, the pressure applied to the laminated | stacked sheet | seat has the preferable range of 1-100 Mpa. If the pressure is less than 1 MPa, the sheets may not be sufficiently integrated and may peel during the subsequent steps. Further, when a pressure exceeding 100 MPa is applied, the deformation amount of the sheet becomes too large.

  The obtained laminate is degreased and sintered in the same manner as the post metallization method described above to obtain a ceramic heater. Degreasing and sintering temperatures and atmospheres, the amount of residual carbon, and the like are the same as in the post metallization method. In addition, when printing the above-mentioned conductive paste on a sheet, it is possible to easily produce a ceramic heater having a plurality of electric circuits by printing a heater circuit and a guard electrode on a plurality of sheets, respectively, and laminating them. Is possible.

  In addition, when an electric circuit such as a resistance heating element is formed in the outermost layer of the laminated sintered body constituting the ceramic heater, the post-metallization method described above is used to protect the electric circuit and ensure insulation. As in the case of, an insulating layer can be formed on the electric circuit. In this way, a ceramic heater made of a ceramic laminated sintered body can be produced.

  The ceramic heater manufactured by the post metallization method or the cofire method as described above then forms a chuck top conductor layer on a predetermined surface. At that time, since the warped shape of the surface does not normally fall within the required accuracy range in the sintered state, the surface on the wafer mounting surface side where the conductor layer is formed is subjected to processing such as polishing, The warp shape is a concave of 0.001 to 0.7 mm / 300 mm. Further, a substantially concentric groove is formed on the wafer mounting surface, and a vacuum suction through hole is formed in the groove.

  Thereafter, a chuck top conductor layer is formed on the surface on the wafer mounting surface side. There are no particular restrictions on the method of forming the conductor layer, but for example, a high melting point metal paste such as tungsten or molybdenum may be applied to the surface and baked, or a noble metal paste such as silver, platinum or palladium may be applied and baked. May be. However, when a refractory metal is applied and fired, warping may newly occur in the ceramic heater, and therefore a method of applying and firing a paste such as a noble metal having a low firing temperature is preferable.

  The firing temperature of these noble metal pastes is preferably 700 to 1000 ° C. At a temperature of 700 ° C. or lower, the grain growth of the noble metal particles does not proceed, so that the resistance value is increased and the adhesion with AlN is also lowered, which is not preferable. Moreover, after forming the conductor layer, it is also possible to apply nickel or the like thereon. In particular, when the conductor layer is a refractory metal, it is preferable to perform plating because the electric resistance value can be lowered and oxidation of the conductor layer can be prevented.

  Also, the chuck top conductor layer can be formed by directly plating the surface on the wafer mounting surface side with nickel or the like. The thickness of the plating in this case is not particularly limited but is preferably 1 μm or more. A plating thickness less than this is not preferable because the resistance value becomes too high.

  Further, the chuck top conductor layer can be formed by a thin film method. In this case, a conductive layer can be formed by first forming a titanium film by vapor deposition, further forming a platinum film thereon by vapor deposition, and vapor-depositing nickel or gold as necessary.

  Further, thermal spraying can be used as a method for forming the chuck top conductor layer. In this case, as a material to be sprayed, a conductive material such as nickel, aluminum, or copper may be appropriately selected. The thickness is not particularly limited as long as a predetermined resistance value can be obtained, but a thickness of 1 to 100 μm is suitable for practical use. If the thickness exceeds 100 μm, the adhesion between the conductor layer and AlN tends to be reduced. Moreover, if thickness is less than 1 micrometer, since resistance value becomes high too much, it is unpreferable.

  In this way, a wafer prober in which a chuck top conductor layer is provided on the surface of the ceramic heater can be manufactured. In the obtained wafer prober, the warp shape of the wafer mounting surface when not heated reflects the shape of the underlying ceramic substrate and becomes a concave shape of 0.001 to 0.7 mm / 300 mm. The surface roughness of the wafer placement surface of the wafer prober is preferably 5 μm or less in terms of Ra. If the Ra exceeds 5 μm, AlN may be shattered by friction with the wafer. The shed particles become particles and adversely affect the wafer processing. Accordingly, the surface roughness is more preferably 1 μm or less in terms of Ra.

[Example 1]
A sintering aid and a binder were added to aluminum nitride (AlN) powder and dispersed and mixed by a ball mill. This raw material slurry was spray-dried and then press-molded into a disk shape having a diameter of 380 mm and a thickness of 20 mm. The obtained molded body was degreased at a temperature of 800 ° C. in a nitrogen atmosphere and then sintered at 1900 ° C. for 4 hours to obtain an AlN sintered body. The thermal conductivity of this AlN sintered body was 170 W / mK.

  The outer peripheral surface of this AlN sintered body was polished to an outer diameter of 330 mm, and the upper and lower surfaces were further polished to a thickness of 15 mm. On one surface of the obtained AlN substrate, a conductive paste obtained by kneading tungsten powder and a sintering aid in a binder was printed and applied to form a predetermined heating element circuit pattern. This AlN substrate was degreased at 800 ° C. in a nitrogen atmosphere and then baked at 1850 ° C. to form a W resistive heating element.

Then, on the resistance heating element excluding the temperature measuring element mounting part and the power feeding part, a crystallized glass paste mainly composed of B ₂ O ₃ and ZnO is printed and degreased at 350 ° C. in the atmosphere. An insulating layer was formed by baking at 700 ° C. in a nitrogen atmosphere.

  Next, the surface opposite to the surface on which the resistance heating element was formed was polished to form a warped shape with the warpage amount shown in Table 1 below for each sample. On the surface having a predetermined warp shape, Ni plating was applied by 5 μm to form a chuck top conductor layer. Furthermore, female electrodes were processed in the vicinity of the electrodes of the resistance heating element, and Mo electrodes subjected to male threads were attached.

  As schematically shown in FIG. 1, the wafer prober thus obtained includes a ceramic heater 4 having a resistance heating element 2 and an insulating layer 3 on one surface of an AlN ceramic substrate 1, and the ceramic heater 4 The resistance heating element 2 and the conductor layer 5 provided on the opposite surface (the amount of warpage is adjusted as described above). Reference numeral 6 in the figure denotes an electrode lead for energizing the resistance heating element 2.

  With respect to these wafer probers, the temperature of the ceramic heater was raised to 200 ° C. by passing a current through the resistance heating element at a voltage of 200V. At that time, the warpage amount at 200 ° C. was measured for the wafer placement surface of the conductor layer, and the results are shown in Table 1 below together with the initial warpage amount. In the warpage amounts in Table 1, + indicates that the warping direction is the + direction (convex), and-indicates that the warping direction is the-direction (concave) (the same applies to the following tables).

  For each wafer prober, a silicon wafer having a thickness of 0.8 mm and a diameter of 300 mm was placed on the wafer placement surface of the conductor layer, and the temperature of the ceramic heater was heated to 200 ° C. At that time, the surface temperature distribution of the wafer at the time of heating was measured to determine the thermal uniformity of the wafer surface. The obtained results are shown in Table 1 below for each sample.

  As shown in Table 1 above, the temperature at which the wafer is heated in the inspection process by setting the initial warpage shape of the wafer placement surface of the wafer prober to a concave shape in the range of 0.001 to 0.7 mm / 300 mm in the negative direction. High flatness of the wafer mounting surface can be obtained in the region, and at the same time, the wafer surface thermal uniformity (± 0.5% or less) required for a wafer prober made of AlN (thermal conductivity 170 W / mK) is achieved. I was able to.

[Example 2]
A sintering aid and a binder were added to silicon nitride (Si ₃ N ₄ ) powder and dispersed and mixed by a ball mill. This raw material slurry was spray-dried and then press-molded into a disk shape having a diameter of 380 mm and a thickness of 1 mm. This molded body was degreased at 800 ° C. in a non-oxidizing atmosphere and then sintered at 1550 ° C. for 4 hours to obtain a Si ₃ N ₄ sintered body. The thermal conductivity of the Si ₃ N ₄ sintered body was 20 W / mK.

The outer peripheral surface of this Si ₃ N ₄ sintered body is polished until the outer diameter becomes 330 mm, and an Ag—Pt paste is screen-printed on one surface of the obtained Si ₃ N ₄ substrate, and fired at 850 ° C. for resistance. A heating element was formed. Thereafter, in the same manner as in Example 1, an insulating layer was formed, and the surface opposite to the surface on which the resistance heating element was formed was polished into a warped shape shown in Table 2 below for each sample. Further, in the same manner as in Example 1, a conductor layer was formed, electrodes and the like were attached, and a Si ₃ N ₄ wafer prober having the structure shown in FIG. 1 was obtained.

  About this wafer prober, the temperature of the ceramic heater was raised to 200 ° C. by passing a current through the resistance heating element at a voltage of 200V. At that time, the warpage amount at 200 ° C. was measured for the wafer placement surface of the wafer prober, and the results are shown in Table 2 below together with the initial warpage amount. Further, a silicon wafer having a thickness of 0.8 mm and a diameter of 300 mm is placed on the wafer mounting surface, and the thermal uniformity of the wafer surface when the temperature of the ceramic heater is heated to 200 ° C. is obtained. It is shown in Table 2.

As shown in Table 2 above, the temperature at which the wafer is heated in the inspection process by making the initial warpage shape of the wafer placement surface of the wafer prober concave in the − direction within the range of 0.001 to 0.7 mm / 300 mm. High flatness of the wafer mounting surface can be obtained in the region, and at the same time, the thermal uniformity of the wafer surface (± 1.0% or less) required for a Si ₃ N ₄ (thermal conductivity 20 W / mK) wafer prober Could be achieved.

[Example 3]
A sintering aid and a binder were added to aluminum oxynitride (AlON) powder and dispersed and mixed by a ball mill. This raw material slurry was spray-dried and then press-molded into a disk shape having a diameter of 380 mm and a thickness of 5 mm. This molded body was degreased at 800 ° C. in a non-oxidizing atmosphere and then sintered at 1770 ° C. for 4 hours to obtain an AlON sintered body. The thermal conductivity of this AlON sintered body was 20 W / mK.

The outer peripheral surface of the AlON sintered body is polished to an outer diameter of 330 mm, and W is 85% by weight, CaO, SiO ₂ , Al ₂ on one surface of the obtained AlON substrate by the same method as in Example 1. A conductive paste having 5% by weight of O ₃ was printed and degreased, and then fired at 1700 ° C. in a nitrogen atmosphere to form a resistance heating element. Thereafter, in the same manner as in Example 1, an insulating layer was formed, and the surface opposite to the surface on which the resistance heating element was formed was polished into a warped shape shown in Table 3 below for each sample. A conductive layer having a thickness of 10 μm was formed on the surface by thermal spraying of Ni, and electrodes and the like were further attached to obtain an AlON wafer prober having the structure shown in FIG.

  About this wafer prober, the temperature of the ceramic heater was raised to 200 ° C. by passing a current through the resistance heating element at a voltage of 200V. At that time, the warpage amount at 200 ° C. was measured for the wafer placement surface of the wafer prober, and the results are shown in Table 3 below together with the initial warpage amount. Further, a silicon wafer having a thickness of 0.8 mm and a diameter of 300 mm is placed on the wafer mounting surface, and the thermal uniformity of the wafer surface when the temperature of the ceramic heater is heated to 200 ° C. is obtained. It is shown in Table 3.

  As can be seen from Table 3 above, the initial warpage shape of the wafer placement surface of the wafer prober is set to a concave shape in the range of 0.001 to 0.7 mm / 300 mm in the negative direction, thereby heating the wafer in the inspection process. High flatness of the wafer mounting surface can be obtained in the temperature range, and at the same time, the wafer surface thermal uniformity (± 1.0% or less) required for a wafer prober made of AlON (thermal conductivity 20 W / mK) is achieved. We were able to.

[Example 4]
A sintering aid was added to the silicon carbide (SiC) powder, an organic solvent and a binder were further added, a slurry was prepared by ball mill mixing, and a disk-shaped molded body was prepared and degreased in the same manner as in Example 1. Then, the SiC sintered compact was obtained by baking at 2000 degreeC in nitrogen atmosphere. The thermal conductivity of this SiC sintered body was 220 W / mK.

  A resistance heating element and an insulating layer were formed on this SiC sintered body in the same manner as in Example 1, and the surface opposite to the surface on which the resistance heating element was formed was polished into a warped shape shown in Table 4 below for each sample. did. A conductor layer was formed on this surface in the same manner as in Example 1, and electrodes and the like were further attached to obtain a SiC wafer prober having the structure shown in FIG.

  Also for this wafer prober, the temperature of the ceramic heater was raised to 200 ° C., the amount of warpage at 200 ° C. was measured on the wafer mounting surface of the conductor layer, and the results are shown in Table 4 below together with the initial amount of warpage. . Further, a silicon wafer having a thickness of 0.8 mm and a diameter of 300 mm is placed on the wafer mounting surface, and the thermal uniformity of the wafer surface when the temperature of the ceramic heater is heated to 200 ° C. is obtained. It is shown in Table 4.

  As can be seen from Table 4 above, the initial warp shape of the wafer placement surface of the wafer prober is set to a concave shape in the range of 0.001 to 0.7 mm / 300 mm in the negative direction, thereby heating the wafer in the inspection process. High flatness of the wafer mounting surface can be obtained in the temperature range, and at the same time, the wafer surface thermal uniformity (± 0.5% or less) required for a SiC (thermal conductivity 220 W / mK) wafer prober is achieved. We were able to.

[Example 5]
For each sample wafer prober obtained in each of the above examples, with the silicon wafer placed on the wafer placement surface and heated to 200 ° C., the probe card was pressed 100 times to check for wafer misalignment. did. As a result, the wafer prober of each sample in the comparative example was displaced by 0.3 mm or more, whereas in the wafer prober of the embodiment of the present invention, no wafer displacement was observed, and the probe All the measurement pins of the card could be applied to the wafer. Further, in the wafer prober of Sample 9 as a comparative example, the wafer was cracked and damaged.

1 is a schematic cross-sectional view showing a wafer prober of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Resistance heating element 3 Insulating layer 4 Ceramic heater 5 Electrode lead

Claims (3)

  A wafer prober for holding and heating a wafer in a semiconductor inspection process, having a conductor layer on the surface of a ceramic substrate, and having a resistance heating element on the surface opposite to or inside the surface on which the conductor layer is formed, the conductor layer The wafer prober is characterized in that the warp shape of the wafer mounting surface is a concave shape of 0.001 to 0.7 mm / 300 mm when not heated.   2. The wafer prober according to claim 1, wherein the ceramic substrate is made of at least one selected from aluminum nitride, silicon nitride, aluminum oxynitride, and silicon carbide. 3. The wafer prober according to claim 1, wherein the resistance heating element is made of at least one selected from tungsten, molybdenum, tantalum, platinum, palladium, silver, nickel, and chromium.

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